A104360 Number of distinct prime factors of A104357(n) = A104350(n) - 1.

0, 1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 2, 2, 2, 1, 2, 3, 3, 1, 3, 3, 3, 1, 2, 4, 4, 2, 2, 5, 4, 2, 3, 2, 3, 1, 3, 4, 3, 5, 3, 4, 4, 5, 1, 3, 4, 2, 2, 2, 3, 1, 2, 3, 2, 3, 1, 4, 1, 3, 4, 6, 4, 4, 2, 6, 1, 5, 4, 4, 1, 2, 5, 7, 4, 5, 3, 4, 4, 5, 4, 5, 2, 4, 4, 5, 3, 3, 3, 2, 5, 2, 5, 4, 7, 2, 5, 3, 2, 6, 3, 4, 2, 3, 3, 3, 5, 4, 3, 5, 2

Offset

2,7

Links

Max Alekseyev, Table of n, a(n) for n = 2..145

Reinhard Zumkeller, Products of largest prime factors of numbers <= n

Formula

a(n) = A001221(A104357(n)).

Mathematica

A104350[n_] := Product[FactorInteger[k][[-1, 1]], {k, 1, n}]; PrimeNu[Table[A104350[n] - 1, {n, 2, 50}]] (* G. C. Greubel, May 10 2017 *)

Crossrefs

Cf. A001221, A054989, A066877, A104350, A104357, A104358, A104359, A104361, A104362, A104363, A104364, A104368.

Sequence in context: A090455 A273190 A086288 * A318998 A079951 A095407

Adjacent sequences: A104357 A104358 A104359 * A104361 A104362 A104363

Keyword

nonn

Author

Reinhard Zumkeller, Mar 06 2005

Extensions

a(51)-a(74) from Amiram Eldar, Feb 12 2020

More terms from Jinyuan Wang, Apr 02 2020

Terms a(90) onward from Max Alekseyev, Oct 03 2022

Status

approved